1. Field of Invention
The present invention relates to a method for producing a hydrophobically finished aramid fabric and the use thereof.
2. Description of Related Art
Hydrophobically finished aramid fibers and fabrics and methods for producing them are known.
WO 95/04854 describes a process for plasma treatment of antiballistically effective materials such as aramids whereby, in a first step, plasma treatment is carried out with ≧50% of an inorganic gas or a mixture of inorganic gases and, in a second step, with a hydrophobically acting organic gas or with a mixture of such gases from the group of saturated hydrocarbons, unsaturated hydrocarbons, saturated fluorocarbons, unsaturated fluorocarbons, siloxanes and vinyl compounds, in the presence of one or more inorganic gases if required.
U.S. Pat. No. 4,232,087 discloses the coating of aramid fibers and/or aramid fabrics (e.g., Nomex fibers) with an aqueous dispersion of polytetrafluoroethylene particles and a water-soluble coordination complex of chromium with a fluoro-substituted hydrocarbon compound containing amino-substituted and sulfonylamino-substituted alkyl groups having ≧6 carbon atoms. The treated fabric is dried, after which crosslinking is advantageously effected by heat treatment.
WO 92/01108 describes the coating of aramid fibers with an aqueous fluoropolymer dispersion, which is applied to the fiber either in the wet or the dried state, whereby, preferably, the wet, never-dried fiber is immersed in a coating bath containing the fluoropolymer dispersion. The coated fiber is then dried, during which the coating on the fiber surface is crosslinked.
U.S. Pat. No. 5,116,682 describes the production of anti-wicking and water-repellent heat-stable yarns, such as polyester yarns or yarns made from glass, nylon or aramid. The yarn is coated with a fluorocarbon emulsion or dispersion, dried and then crosslinked by heat.
Aramid fabrics are known to show high antiballistic efficiency in the dry state. However, the antiballistic efficiency is considerably reduced when the fabric is in the wet state. Aramid fabrics are therefore often given a hydrophobic finish. It has been shown, however, that aramid fabrics provided with a hydrophobic finish by the known methods nevertheless show a significant reduction in their protective antiballistic efficiency when they are wet.